every engine is differnt, as is every gallon of gas, to say dyno this or engine that, you have to match paramaters exactly, combustion chamber shape, timming advance, head material, and of course the fuel specific gravity. All gasoline is blended a bit differnt, summer, winter, altitude, sea level, every manufacture has a few differnt widgets they add or don't add that really changes whats perfect for a tune.

Gasoline on that combination that day might have been pump gas, and might have had a bunch of alcohol in it. OR conversly, could have been high end race gas with lots of knock inhibitors in it, and that combination might have been running 36 degrees advance on a small combustion chamber......... etc.